1. Field of the Invention
This invention relates generally to an apparatus for determining the grip length of a hole that extends through a stack of panels so that a suitable fastener can be selected for insertion into the hole.
2. Description of the Related Art Including Information Disclosed Under 37 CFR 1.97 and 1.98
Known fastener grip length measurement systems include a clamping or “grip gun” type measurement device that includes a fixed hook-like probe carried on a distal end of a shaft extending from a handle. A sliding probe is supported on the handle for reciprocal motion generally parallel to and along the shaft in opposition to the fixed probe. The fixed probe is inserted through a hole to be measured, e.g., a hole extending through a stack of two or more panels, and is engaged against a far, opposite-facing surface of the panel stack. The sliding probe is then clamped against a near surface of the panel stack, sandwiching the panel stack between the two probes. The space between the two probes is then measured by an encoder that generates and sends a corresponding signal to electronic circuitry that calculates a desired grip length for a fastener to be selected for the hole. The electronic circuitry then sends a corresponding grip length reading to a remote device such as a 3D optical projection system. The 3D optical projection system associates the grip length reading with the location of the hole and can subsequently direct that an appropriately sized fastener be mounted in the hole in that location.
Ball plungers are known for use as position sensors that generate a confirmation signal when the ball of a ball plunger sensor carried by one object is driven out of or into a ball detent carried by a second object. Contact sensor-type ball plungers are known to include a ball carried within a generally cylindrical sleeve or canister that has an opening at one end and a ball retainer detent or forward stop adjacent the opening. A spring is generally disposed between the ball and a closed end of the sleeve in a position to bias the ball toward the opening and into a position against the forward stop with a portion of the ball protruding through the opening. A signal output sensor is carried by the sleeve in a position to sense ball depression.